Air distribution means for a refrigerated meat case

ABSTRACT

This is a refrigerated display case in which the refrigerated air enters the refrigerated space at a very low velocity from the top of this space and descends vertically substantially by gravity through the space and is exhausted from the bottom thereof.

United States Patent Butts 1 1 AIR DISTRIBUTION MEANS FOR A REFRIGERATED MEAT CASE [75] Inventor: Edward E. Butts, Niles. Mich.

[731 Assignee: Clark Equipment Company.

Buchanan. Mich.

[22] Filed: Apr. 4, 1974 [21] Appl. No.1 457,959

[52] US. Cl 62/256: 62/89 [51] Int. Cl. A47f 3/04 [58] Field of Search 62/255. 256, 89

[561 References Cited UNITED STATES PATENTS 2.466.286 4/1949 StuItz 62/255 2.836.039 5/1958 Weber 62/256 1 1 June 10,1975

3.021.691 2/1962 Jacobs 62/256 3.063.252 11/1962 Liimb 62/256 3.063.255 11/1962 Farrick 62/256 3115.01) 12/1963 RU[1S1'111USCl'.. 62/256 3.218.822 11/1965 Bentiy 62/256 3.306.068 2/1967 A1ge ver...... 62/255 3.369.375 2/1968 Gerwcck.... 62/256 3.501.925 3/1970 Brennan 62/256 Primary Exunu'rwrWi11ium J. Wye Azmmey. Agent. or FirmHurry G. Thihziult {57] ABSTRACT This is a refrigerated display case in which the refrigerzited air enters the refrigerated space at a very low velocity from the top of this space and descends VCTI1 Cally substantially by gravity through the space and is exhausted from the bottom thereof.

6 Ciaims, 3 Drawing Figures PATENTEUJUH 10 1975 FIG. 3

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lllllllIIIIIIIIIIII111]!Ill!l11|||IIIIIIIIIIIIIIIlllllllllllllllllllllllIII lllllll lllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllll]IIIIIIITT lll|||lvllll||llllllllllllllllllllllll|llllllllllllllllllllllllllllllllIlllllllllll AIR DISTRIBUTION MEANS FOR A REFRIGERA'I'EI) MEAT (ASE BACKGROUND AND SUMMARY OF THE INVENTION This invention relates to refrigerated display cases of the type having a substantially vertical low velocity flow of refrigerated air through the refrigerated space. In the present invention. the refrigerated air enters the refrigerated space over a substantial area over the top of the space and circulates through the space substantially by gravity and is exhausted at the bottom thereof. The air is exhausted from the lower area ofthe refrigerated space by an air circulating means located in a plenum chamber under the space. It is then circulated through refrigerating coils and up an enclosed duct to a plenum chamber at the top of the refrigerated space. The air is thereafter reintroduced into the refrigerated space by either a large number of louvers or through porous material. The air moves vertically across the refrigerated space substantially by gravity.

In one particular modification of present invention, the air is exhausted through a louvered or porous top of the refrigerated space so as to move vertically hrough the space while in a second modification of this invention, the air is moved from the upper plenum chamber through diverging grille sections down past divergings front and rear sections of the case to be at on the bottom thereof. In this latter modification of the invention the air is exhausted from the overhead grilles at a velocity sufficient to form wide slow moving refrigerated air curtains at both the front and rear of the case. In both modifications. a single air circulating and air refrigeration means is utilized and the air circulates downwardly past the refrigerated material at a low velocity.

In the present invention, the refrigerated air is introduced at the top of the refrigerated space at a very low velocity and drifts down across this space to be exhausted at the bottom thereof. The ambient air outside the refrigerated space being warmer and therefore lighter than the refrigerated air does not enter the refrigerated space in any substantial quantity even with an open case. The cold air may fill the case to the lip at the lower side of the opening. thus excluding the warmer ambient air from entering the case.

The prior art shows a large number of refrigerated display cases in which a high velocity refrigerated air curtain is used to insulate the refrigerated space from ambient air. and some of these have a refrigerated air circulating through the refrigerated space. for example. see U.S. Pat. No. 3.392.543 Miller.

Other prior art shows refrigerated display cases in which the cold air is propelled horizontally through the refrigerated space. for example. U.S. PAt. No. 3.324.783 I-Iickox.

In each of the patents noted above. the air is propclled at sufficient velocity to transport the air from the entrance to the exit of the refrigerated space. If the air is of low humidity. this elocity is sufficient to cause dehydration of the refrigerated food on which it may impinge.

In the present invention. the air is propelled at a very low frontal velocity and in the ideal case. descends by gravity to displace the air being drawn out at the bottom of the refrigerated space.

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It is therefore an object of the present invention to provide a refrigerated display case which substantially excludes warm ambient air without the use of high ve locity air curtainsv It is another object of the present invention to pro- \ide a refrigerated display case in which the differential in air pressure necessary to move the refrigerated air is held at a minimum thereby conserving the energy required to circulate the refrigerated air.

It is another object of the present invention to pro vide a refrigerated display case from which refrigerated articles may be stored in an area of substantially still cold air.

It is another object of the present invention to replace the high velocity air curtains normally used on refrigerated display cases with a broad band low velocity air curtain.

BRIEF DESCRIPTION OF THE PREFERRED EMBODIMENT Referring to the figures in the drawings:

FIG. I is a cross section of one modification of the present invention in which the refrigerated air flows substantially vertically through the refrigerated space:

FIGv 2 shows the second modification of the present invention in which the refrigerated air flows in diverging wide slow moving air bands down through the refrigerated space;

FIG. 3 is a front view of the modification shown in FIG. 2 which is substantially the same as a front view of the modification in FIG. I which latter front view is unshown.

Referring now more particularly to FIG. 1, 2 is the top of the refrigerated display case shown generally as 4 having a refrigerated air plenum chamber 6. Air is exhausted from plenum chamber 6 through a perforated or porous plate 8 and Iouvers 10 into a refrigerated air space 12 in which space the articles to be refrigerated. usually foodstuffs, are supported on a tray 14. This tray 14 may be either substantially solid or produced from wire mesh. Located below the horizontal tray 14 is a plenum chamber I6 into which the air flows through a passage 18 in front of the support and a similar passage 20 in the rear thereof in addition the air may flow through the tray 14 if this tray is made of wire mesh or other perforated material. The air from the lower plenum chamber I6 is exhausted therefrom by means of air moving means 22 here shown as an electric motor fan into an air return duct 24 having an air cooling means 26 therein. The air cooling means is normally an evaporator or chilling coil. The air circulates up through the duct 24 through a perforated baffle 28 into the upper plenum chamber 6.

The air pressure in the plenum chamber 6 is maintained slightly greater than that in the lower plenum chamber 16 by means of the fan or other circulating device 22. The air is thereby forced into the refrigerated space 12 through the porous or perforated member 8 and through the louvers I0. This air is then exhausted from this refrigerated space into the plenum chamber 16 through the openings 18 and 20. If the support I4 is porous the air may also pass through that member.

The operation of the modification of the invention shown in FIG. 1 is as follows.

The evaporator or chilling coils 26 are first cooled. through a refrigeration system of common design not shown. to the desired temperature and the fan or other air propulsion means 22 is started. The foodstuff to be displayed in the case is placed on the horizontal support 14.

Air is exhausted from the lower plenum chamber 16 by the air propulsion means 22 past the cooling coils 26 where it is cooled and then the air travels upward through the duct 24 and into the upper plenum chamber 6 where it is distributed evenly and passed through the perforated diffuser thereof 28. The pressure of the air in the plenum chamber 6 being greater than that in the refrigerated space, it is forced through the perforated or porous member 8 and through the louvers 10 into the refrigerated space 12. It travels through this space substantially by gravity and due to the pressure being higher in the refrigerated space 12 than in the lower plenum chamber 16. The air traveling through the refrigerated space 12 cools the displayed foodstuff stored therein. Since the air is recirculated and travels at a very low velocity over the foodstuff, a minimum of moisture is lost and the drying of the foodstuff is main tained at a minimum.

Referring now to FIG. 2., a second modification of the present invention is illustrated in which the refrigerated air instead of flowing in a vertical direction is divided and flows in two diverging slow moving broad bands down through the refrigerated space.

Referring more particularly to FIG. 2, 34 refers gen erally to the refrigerated display case with a refrigerated space 42 having therein a support 44 on which the product to be refrigerated may be placed. 46 is a lower plenum chamber into which the refrigerated air is exhausted from the space 42 through the openings 48 and 50 which are at the front and back respectively of the support 44. 52 is an air propulsion means here shown as a fan and 56 is an air cooling means here shown as the evaporator coil or chilling coil of a refrigeration system of common design not shown. 54 is an air duct which supplies air to the upper plenum chamber 36 through the perforated panel 58. The air is exhausted from the upper plenum chamber 36 through the porous plate 38 into secondary upper plenum chambers 37 and 39.

The air from the plenum chamber 37 is exhausted in the general direction of the opening 50 by the grille 41. In a like manner the air from the secondary plenum chamber 39 is exhausted in the general direction of the opening 48 by the grille 40.

The refrigerated air in the refrigerated space 42 is exhausted through openings 48 and 50 extending the length of the case by the fan or other air propulsion means 52 exhausting air from the lower plenum chamber 46 thereby maintain the air pressure in this plenum chamber at a lower pressure than that in the refrigerated space 42. The air is then forced past the refrigerating coils 56 and up the duct 54 and through the perforated plate 58 into the upper plenum chamber 36. The purpose of this plenum chamber 36 is to distribute the air at an equal pressure along the length of the case and thereby cause the air to be exhausted uniformly into the secondary plenum chambers 39 and 37. The air in these plenum chambers is at a substantially equal pressure and at a pressure greater than that of the air in the refrigerated space 42, thus causing the air to be exhausted substantially by gravity through the grilles 40 and 41 towards the openings 48 and 50 respectively which run the length of the case.

It may therefore be seen that the air introduced into the refrigerated space through the grilles 40 and 41 flows down over the products resting on the support 44 to refrigerate these products and the slightly warmer air after refrigerating the products is exhausted into the lower plenum chamber 46 and back past the cooling coils 56 to have its temperature reduced and start its circulation cycle all over again It may thus be seen that the present invention provides a refrigerated case having a substantially vertical current of very slow moving air which envelopes the products in the refrigerated space to thereby cool the product and minimize the removal of moisture therefrom.

Having thus described the preferred embodiment of the present invention, it will be, of course, be understood that various changes may be made in the form, arrangements and proportion of the parts without departing the scope of the invention which consists of the matter shown and described herein and set forth in the appended claims:

I claim:

1. A refrigerated display case having a refrigerated space and including:

a support for articles to be stored in said refrigerated space.

a plenum chamber located above said support,

a second plenum chamber located below said support, an air duct between said second plenum chamber and said first plenum chamber including therein,

means for maintaining the air in said second plenum chamber at less than atmospheric pressure and maintaining the air in said first plenum chamber at greater than atmospheric pressure,

cooling means located in said air duct capable of maintaining the temperature of said air in said first plenum chamber lower than the temperature of the air in said second plenum chamber,

porous conductive means located between said first plenum chamber and said refrigerated space capa' ble of restricting the flow of air so as to diffuse the air as it passes from said first plenum chamber to said refrigerated space,

whereby air is exhausted from the lower portion of said space into said second plenum chamber and thereafter circulated by said cooling means through said air duct to said first plenum chamber and moved through said porous conductive material from said first plenum chamber into said space and by gravity through said space to said second plenum chamber, to thereby cause the circulation of cool air through said space and past said support in a manner substantially equal to gravity flow.

2. A refrigerated display case as claimed in claim 1 in which:

said display case has an access opening in the front thereof for unimpeded access to the refrigerated space.

3. A refrigerated display case as claimed in claim 1 in which:

the supports for said articles to be refrigerated is impervious whereby the air circulating through said space to said second plenum chamber must bypass said support.

4. A refrigerated display case as claimed in claim 1 in which:

6 the air is directed downwardly in two diverging broad said support.

bands 9 510w mQvmg 6. A refrigerated display case as claimed in claim 2 5. A refrigerated display case as claimed in claim 2 In WhlCh. in which: h d d d] b the supports for said articles to be refrigerated is imt e g (fwnwar y In two wergmg pervious whereby the air circulating through said of Slow moving am space to said second plenum chamber must bypass 

1. A refrigerated display case having a refrigerated space and including: a support for articles to be stored in said refrigerated space, a plenum chamber located above said support, a second plenum chamber located below said support, an air duct between said second plenum chamber and said first plenum chamber including therein, means for maintaining the air in said second plenum chamber at less than atmospheric pressure and maintaining the air in said first plenum chamber at greater than atmospheric pressure, cooling means located in said air duct capable of maintaining the temperature of said air in said first plenum chamber lower than the temperature of the air in said second plenum chamber, porous conductive means located between said first plenum chamber and said refrigerated space capable of restricting the flow of air so as to diffuse the air as it passes from said first plenum chamber to said refrigerated space, whereby air is exhausted from the lower portion of said space into said second plenum chamber and thereafter circulated by said cooling means through said air duct to said first plenum chamber and moved through said porous conductive material from said first plenum chamber into said space and by gravity through said space to said second plenum chamber, to thereby cause the circulation of cool air through said space and past said support in a manner substantially equal to gravity flow.
 2. A refrigerated display case as claimed in claim 1 in which: said display case has an access opening in the front thereof for unimpeded access to the refrigerated space.
 3. A refrigerated display case as claimed in claim 1 in which: the supports for said articles to be refrigerated is impervious whereby the air circulating through said space to said second plenum chamber must bypass said support.
 4. A refrigerated display case as claimed in claim 1 in which: the air is directed downwardly in two diverging broad bands of slow moving air.
 5. A refrigerated display case as claimed in claim 2 in which: the supports for said articles to be refrigerated is impervious whereby the air circulating through said space to said second plenum chamber must bypass said support.
 6. A refrigerated display case as claimed in claim 2 in which: the air is directed downwardly in two diverging bands of slow moving air. 